Spectroscopy is the study of the interaction between matter and radiated energy. Spectroscopy is known to be used for many applications in physics, chemistry, biology and the environmental sciences. Some current spectroscopy systems use a frequency comb as a light source. In general, a frequency comb is a light source whose frequency domain spectrum includes a series of discrete, equally spaced elements (frequency lines). In the time domain, the frequency comb emits a train of optical pulses with a carrier frequency and a repetition rate. Frequency comb sources may be useful for spectroscopy applications, because they can provide simultaneous broad spectral coverage (e.g., spectral coverage on the order of hundreds to thousands of frequency comb lines) and high resolution (e.g., an optical resolution typically better than about 10 MHz), broadband measurements of molecular samples.